Design And Implementation Of Embedded Video Phone Based On ARM9 Platform

With the development of communication technique, people had more requests for telecom services. Thus, video phone emerged as the times require. Early video phone was based on PSTN network. But it has been vanishing from history because its bitrate lower than 64kbps can't satisfy video communication. After that, video phone based on ISDN turned up whose bandwidth can satisfy video communication. But it is restricted by ISDN's unpopularity.With the development of IP technique, real-time video and audio transmissions through IP network have become possible. The maturity of VoIP, RTP, H.323 and SIP, provide video phone uniform technique standard and establish the foundation for video phone to develop rapidly.Most of present IP video phone is dependent on PC. Terminal of video phone based on embedded system and similar to traditional phone must be exploited to make the video phone popular.The main contributions in this thesis are as follows:(1) A solution to embedded video phone terminal based on ARM9 platform and Linux OS is proposed;(2) The structure of video phone system is optimized to match the feature of embedded system hardware. System data throughput and efficiency is improved by multithread;(3) G.729A and H.263 are transplanted to ARM9 platform. The C code is optimized and some functions are realized with assemble language to satisfy the system's real-time demand, while the performance is maintained;(4) Simulation test is performed by communication between PC and ARM emulator to evaluate the function and performance of the video phone system.Results of the simulation test indicate that the basic function such as real-time capture, coding, RTP packet, net transmission, RTP unpacking, decoding and display of speech and video data are realized and fluent video image, clear sound and real-time feature are achieved.